The 41-year-old lives in Windsor, Berkshire, and bought the house for £130,000 while his son was studying at Swansea university. After refurbishing the property, he decided to rent it out.

Mr Ljeoma was told by his new tenant the home would be occupied by four people. After meeting the man, the lease was signed and the tenants moved in.

He said: “About six months in, I visited the house and everything seemed in order.”

But in what he now calls a “naive” move, he gave the tenants his only keys to the property, meaning he was unable to make regular checks when the tenants stopped regular contact.

“The rent kept coming in regularly, so I thought everything was fine,” he said.

“I now realise it was pretty naive of me.”

“I’d like to warn other landlords to keep a close eye on their properties, because you never know what could happen.”

Until last Sunday’s fire, there was no hint of trouble at the property for 18 months.

With no insurance on the property, Mr Ljeoma will have to pay the costs to fix the destroyed house, which he estimates will cost around £50,000 to £60,000.

He now plans to turn the house into flats.

“I’m not put off from renting properties, but I will be a lot more cautious in future,” he said.

“The real kicker is, I had planned to come down this week anyway to check up on them. If only it had been a week sooner.”

The cause of the fire is still under investigation by South Wales Fire and Rescue and the South Wales Police fire investigation team.

No arrests have been made.

Obi Ljeoma invited WalesOnline in to see the damage. Here is what we saw:

Walking through the front door, still bearing the marks of firefighters’ attempts to enter the house mid-blaze, the devastation is clear even from the living room, which the fire barely reached.

The blackened stairs are covered in soot and crumbled tiles, while the stench of smoke and cannabis fills the entire house. Each of the three bedrooms on the middle floor have been completely gutted by the blaze. The only way to tell which was a bathroom and which was a bedroom is from the remnants of a sink and a shower lying in the rubble.

Remnants of cannabis plants lie among the ashes along with singed clothing. In one bedroom, a row of overloaded plug sockets dominate a wall, surrounded by copper wiring.

The roof is almost completely destroyed, with the top floor bared to the elements.